This study was designed to accurately identify Cynoglossus eggs and larvae (Cynoglossus sp.), and to accumulate base data for further study on the taxonomy and early identification of Cynoglossus fishes. Cynoglossus sp. samples were collected in Qingshan Bay, Qingdao, between May and October 2015. Three eggs, 3 larvae and a total of 5 individuals from 2 species (C. joyneri and C. lighti) in the Jiaozhou Bay area were barcoded using COI, sequenced, and compared with 6 Cynoglossus species found in the Shandong Peninsula and recorded in GenBank. Under a light microscope, the egg had a circular shape and floated within a wider perivitelline space; eggs ranged in diameter from 0.68 to 0.87 mm with a mean diameter of 0.73±0.03 mm; eggs had a single layer membrane and were smooth and transparent; the oil globules were located opposite the yolk sac, ranged from 6 to 15 in number, and diameter ranged from 0.04 to 0.10 mm (mean diameter: 0.07±0.01 mm); there were obvious characteristics including the 2 dorsal fin rays and pigmentation and body length changes in the period of metamorphosis for larvae identification. Results of genetic analysis showed that the average K2P distances pairwise-species in Cynoglossus sp., C. joyneri and C.lighti ranged from 0.006 to 0.009, and was 0.002 for C. abbreviatus and C. purpureomaculatus. The two groups were placed in two different clades with the support of a high bootstrap value and had a close genetic relationship, separately. The neighbor-joining (NJ) phylogenetic trees were constructed for COI gene sequences of 8 species using MEGA 6.0, and Zebrias zebra was included as an outgroup. The above analysis and results showed that the Cynoglossus sp. is C. joyneri.